Rapid Conformational Epitope Mapping of Anti-gp120 Antibodies with a Designed Mutant Panel Displayed on Yeast

gp120 is a substrate for protein engineering both for HIV immunogen design and as a bait for isolating anti-HIV antibodies from patient samples. In this work we describe the display of a stripped core gp120 on the yeast cell surface. Validation against a panel of neutralizing antibodies confirms that yeast-displayed gp120 presents the CD4 binding site in the correct conformation. We map the epitope of the broadly neutralizing anti-gp120 antibody VRC01 using both a random mutagenesis library and a defined mutant panel, and find the resultant epitope maps are consistent with one another and with the crystallographically identified contact residues. Mapping the VRC01-competitive antibodies b12 and b13 reveals energetic differences in their epitopes that are not obvious from existing crystal structures. These data suggest mutation sets that abrogate binding to broadly neutralizing antibodies with greater specificity than the canonical mutation D368R, useful in rapidly assessing the nature of a vaccine response. ⺠Engineered gp120 are used as immunogens and as bait for isolating anti-HIV antibodies. ⺠Stripped core gp120 presenting the CD4 epitope is displayed on the yeast cell surface. ⺠Rapid conformational epitope mapping of antibody VRC01 is performed by two methods. ⺠Mapping of b12 and b13 captures subtle energetic differences between similar epitopes. ⺠Maps suggest mutations that may better identify and assess neutralizing antibodies.